1. Field of the Invention
The present invention relates to a double-surface (both-side) machining system particularly for grooving front and back surfaces (both sides) of a plate having no sufficient self-standing stiffness.
2. Description of the Related Art
In a known art, front and back surfaces of a plate having a large size (large-dimensional plate) such as a component of a large system such as a power-station equipment or particle accelerator have been grooved by mounting a plate as a workpiece on a surface plate and end-milling the plate one at a time side with an end mill (ball end mill) such as a large gantry mill; carrying the workpiece with a large angle rest and end-milling the workpiece one side bat a time with a large horizontal boring machine and an end mill; or mounting the workpiece on a rotary table and side-cutter-machining the workpiece one side at a time with a large horizontal boring machine and a side cutter.
In any one of the known cases mentioned above, the workpiece is grooved only one side at a time and that is, the front and back surfaces are to be separately grooved. Therefore, a lot of working time including arrangement working has been required. Particularly, in the case of end milling, a lot of working time has been required and a cutting efficiency has been low.
Moreover, although the side-cutter-machining provides an improved cutting efficiency compared with end milling machining, there is a possibility for the workpiece of drooping and deforming due to its own weight, and thereby, its flatness is deteriorated, which may result in a case that when the one-side machining is performed, the grooving may not be performed unless the large plate-like workpiece has a sufficient self-standing stiffness.